1. Technical Field
The present invention relates to a method and a system for determining deterioration of permanent magnets of an electric apparatus including a mover, a stator, a plurality of permanent magnets provided at one of the mover and the stator, and an armature winding provided at the other of the mover and the stator.
2. Related Art
An electric apparatus such as an electric motor may become unable to exhibit its original performance if permanent magnets provided at a mover or a stator are broken, chipped, demagnetized, or anyway deteriorated. If the permanent magnets are broken or chipped, scattered fragments of the permanent magnets may damage components of the electric apparatus. Conventionally, it is determined whether or not the permanent magnets are deteriorated by dismantling the electric apparatus for a visual inspection, or based on how much induced voltage is reduced as described in Japanese Patent Application Publication No. 2009-22091 (JP2009-22091A).
In order to examine deterioration of the permanent magnets through a visual inspection, however, it is required to stop an operation of the electric apparatus to be inspected, and to dismantle the electric apparatus after removal from a facility where it is installed. In addition, it is difficult to quantitatively collect inspection data because the visual inspection is performed with human eyes. If only the induced voltage is examined as in the technique disclosed in JP2009-22091A, local demagnetization, breakage, and chipping of the permanent magnets may not be reliably detected.